The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Propulsion units for aircrafts generally include a nacelle forming an external envelope which is generally circular and which comprises, inside, a turbojet engine disposed along the longitudinal axis of this nacelle.
The turbojet engine receives fresh air coming from the upstream or front side, and discharges at the downstream or rear side the hot gases which result from the combustion of fuel and which deliver a certain thrust. In bypass turbojet engines, fan blades which are disposed around this turbojet engine generate a significant secondary cold air flow which is conveyed along an annular flow path extending between the engine and the nacelle, thereby adding a high thrust.
Some nacelles include a thrust reverser system which closes, at least in part, the annular cold air flow path, and which discharges the secondary flow forward in order to generate a backward thrust for braking the aircraft.
A known type of thrust reversers, presented in particular in Document FR-2960918 A1, includes two movable half-portions which form rear cowls and which can slide axially backward under the action of cylinders, thereby deploying flaps in the annular flow path in order to close this flow path, at least in part, and redirect the cold air flow radially outward through cascades which are uncovered during this sliding and which comprise blades which direct this flow forward.
Another known type of thrust reversers, presented in particular in Document WO-2008/142243 A1, includes the rear of the nacelle doors which are actuated by cylinders and which tilt in order to close the annular flow path, at least in part, thereby deflecting the cold flow radially outward, these doors then direct the flow forward so as to generate the braking thrust.
Moreover, in order to carry out maintenance operations, or to disable the thrust reverser, for example in the event of a failure, it is known to dispose a first manual control on the nacelle, which control acts, when activated, on the motor-actuated system which may be hydraulic, electric or pneumatic, in order to prevent deployment of this thrust reverser. For the same purpose, it is also known to dispose a second manual blocking control, which control acts when mechanically activated and which comprises, for example, an axle connected to the control by means of a rod, which is introduced between the rail and the guide glider of the movable portions of a cascade-type thrust reverser, in order to prevent any displacement of these portions.
The two controls of the motor-actuated and mechanical system are independent of each other, an operator being capable of activating either one of these controls, or both, in order to prevent the deployment of the thrust reverser.